Hi,
I've just built a ADS-B Raspberry Pi receiver/server powered by a USB battery pack.
I also made it an homebrew 1090Mhz half-wave dipole antenna. The results are great and can run for about 4 hours with the current battery.
Anyway, have a look at the blog. I'm interested if anyone else has done something similar.
http://glynne-bashbashbash.blogspot.co.uk/2014/09/homebrew-1090-ads-b-raspberry-pi-remote.html
The only thing missing to increase performance is some Hak5 stickers :-)
Regards
Glynne